Roller coating system for one side strip coating

ABSTRACT

This invention relates to a new and unobvious apparatus for depositing fluids onto one side of a continuous strip and more particularly to depositing a fluid, generally of low viscosity, onto one side of a metal strip without depositing any of the fluid onto the other side of the strip.

United States Patent Carter et a1.

1 1 Feb. 13, 1973 ROLLER COATING SYSTEM FOR ONE SIDE STRIP COATING Inventors: William A. Carter, Gary; William C.

Sievert, Chesterton; James L. Munson, Highland, all of Ind.

Assignee: lnlandSteel Company, Chicago, 111.

Filed: Nov. 23, 1970 App]. No.: 91,914

U.S. Cl. ..ll8/246, 118/259, 118/262, 117/111 R Int. Cl ..B05c l/00 Field of Search ..l18/246, 258, 259, 262; 117/111 R, 111 A, 111 B, 111 C, 111 F, 111

[56] References Cited UNITED STATES PATENTS 3,097,968 7/1963 Schaefer ..118/259 2,724,363 ll/l955 3,162,545 12/1964 Dearsley ..118/259 X Primary Examiner-James Kee Chi Att0meyMerriam, Marshall, Shapiro & Klose 5 7 ABSTRACT This invention relates to a new and unobvious apparatus for depositing fluids onto one side of a continuous strip and more particularly to depositing a fluid, generally of low viscosity, onto one side of a metal strip without depositing any of the fluid onto the other side of the strip.

7 Claims, 1 Drawing Figure ROLLER COATING SYSTEM FOR ONE SIDE STRIP COATING BACKGROUND OF THE INVENTION In the coating of strips of material suchas metal, it is often desired to coat one side of the material without coating the other side. For example, in the process of galvanizing metal, a continuous metal strip is coated on one side with a material which will prohibit any galvanizing occurring on that side of the material. Subsequently, the strip is subjected to a hot dip galvanizing step which will coat one side of the strip with zinc but will not coat the previously coated side of the strip.

A number of drawbacks exist with respect to coating systems presently available for use in coating continuous strips. These systems which employ one or more rollers in the system for applying a fluid to a strip have DESCRIPTION OF THE EMBODIMENT Referring to the drawing, there is shown a continuous strip which is to be coated with a fluid on one side of the strip only. As strip 10 progresses toward the vertically and horizontally.

been found deficient due to their tendency to permit the fluid to coat more than one side of the strip, i.e., the fluid wraps around the strip onto the side where no coating is desired. Another disadvantage found with some prior art coating systems is that the systems produce a coating with large, differences incrOss-sectional thickness across the strip width or in some instances, leave uncoated areas.

It would be advantageous to have a coating system which permits uniform coating of a strip with a fluid, including those that have low viscosities (essentially water), with thecoating being deposited on one side of the strip only with no wrap-around of the fluid'to the other side of the strip.

SUMMARY OFTHE'INVENTION The invention disclosed andclaimed herein relates to a coating system which utilizes a new and novel arrangement of rollers whereby a continuous strip of metal will have a film of low viscosity fluid uniformly deposited on one side of the two sides of the strip with no fluid wrap around onto the remaining side of the strip.

The system involves passing a continuous metal strip over an entry backup roll, under an applicator roll spaced horizontally from the 'entry backup roll and over an exit backup roll. At. the time the strip contacts the applicator roll, a metered amount of fluid is deposited uniformly on one sideof the strip without any occurrence of fluid wraparoundonto the other side of the strip.

The system also includesa metering roll which is ad-; justably positioned relative to and in association with the applicatorroll. Additionally, a solution feed nozzle for dispensing fluid to be deposited upon the strip is placed relative to the applicator roll in a manner to 'be described hereafter in greater detail.

Other features and advantages. are inherent in the structure claimed or disclosed or will be apparent to those skilled in the art from the foregoing detailed description in conjunction with the accompanying diagrammatic drawing.

DESCRIPTION OF THE DRAWING The drawing discloses a fragmentary side view of a portion of a continuous strip situated relative to the strip coating system of the present invention.

As strip 10 moves further along in its horizontal travel, it passes a fluid depositing station 11 at which location, a uniform, fluid coating is deposited on one side of the strip.

Station 11 comprises a applicator roll 13, fluid feed means 14 and a fluid metering roll 15. As shown in the drawing, roll 13 is positioned so that strip 10 will pass under it with roll 13 contacting the strip sufficiently to depress the strip slightly downward relative to the horizontal position of the strip at entry backup roll 12 and exit backup roll 17 Thefluid feed means 14 is positioned contiguous to applicator roll 13 so that fluid exiting from nozzle 16 will fall on roll 13. The fluid deposited on roll 13 falls by means of gravity along the face 9 of applicator roll 13, which, in operation, rotates counterclockwise toward the nozzle 16 as depicted in the drawing. The fluid flow rate down the face 9 of roll 13 is regulated so that the interface or nip 18 is kept sufficiently dammed up'or full of the fluid whereby it spreads laterally across the width of strip 10. While fluid feed means 14 has been shown with nozzle 16 positioned to drop a coating fluid on roll 13, fluid feed means 14 could be positioned to theright of or in advance ,of roll 13 in which case the fluid would be deposited directly on strip 10. Means 14 can be located in advance of roll 13 so long as a dam of fluid is developed at the interface of roll 13 and strip 10 as shown in the drawing.

Because of the pressurecreated by the depression of strip l0 at station 11, relative to the location of the strip at the roll-strip interfaces 20, 21, the fluid is squeezed away or forced outward from the edges of the strip with sufficient force toprevent the fluid from being drawn onto the bottom side 22 of strip 10 where no coating is desired. It will be observed that the depression of strip 10 at station 11 is the lowest or most depressed point in the system. The fluid which has been squeezed away is permitted to drip into one or more pans 8 located below each edge of the strip. The fluid drippage occurs approximately one-half inch away from the respective edges'of the strip. I

As roll 13 rotates in a counterclockwise manner, a layer of fluid, which wets the roll along the width of the roll at the interface 18 'of the applicator roll and strip, is deposited on face 9 of the roll and-is drawn up and around roll l3 to the nip 24 formed at the interface of roll 13 and metering roll 15. The latter roll is carefully adjusted and controlled relative to roll 13 to provide for a uniform fluid thickness to be deposited on surface '23 of strip 10. The fluid poolformed atnip 24 is fluid plicator roll 13 to properly regulate the depositing of fluid on only one side of strip 10. if entry backup roll 12 is positioned too close to roll 13 in the horizontal direction or roll 12 is adjusted vertically so that interface 20 is too high above the interface 18 in a vertical direction, the coating fluid will tend to wrap around the strip to surface 22. However, by depressing applicator roll 13 until the strip is wetted along its entire width and then moving backup roll 12 horizontally away from roll 13 until the wrapping around of the fluid onto surface 22 ceases, the desired coating of one side of a strip with a uniform coating is achieved. It has been found that it is necessary to wet strip 10 on the upstream side of roll 13 or as it goes under roll 13 in order to provide the desired uniform coating on the strip.

Even strips which have edges which have a wave-like configuration at their edges are capable of receiving the one side, uniform fluid coating with the system disclosed and claimed herein.

It has also been found that if the metering roll-applicator roll gap is preset (i.e. held constant), and the solution feed nozzle 16 is moved from the position shown in the drawing to a feed position at 24, the strip develops nonuniform coating streaks. This would seem to indicate that although the strip is in contact with the applicator roll 13 under a fair amount of pressure, some solution or fluid may be entrapped in the surface roughness of strip 10 and drawn beneath applicator roll 13, aiding in the wetting of the strip on the exit side of the roll where the roller coating film is being deposited. lt also may be that the applicator roll face 9 being wetted throughout its entire rotation (except in the small arc of contact with thestrip) aids in drawing a uniform film through the metering roll-applicator roll gap. If the metering roll gap is closed completely, strip 10 emerges from the roller coater with no visably apparent coating on it.

The ultimate coating thickness can be controlled by varying the speeds of the applicator roll, metering roll and the strip in addition to controlling the gap between the metering roll and applicator roll 13.

The foregoing detailed description has been given for simplicity and clearness ofunderstanding only, and no unnecessary limitations should be understood therefrom as modifications will be obvious to those skilled in the art.

What is claimed is:

1. Apparatus for depositing fluid on a strip top side, said apparatus comprising:

a first roll means positioned to be disposed below and in contact with a strip bottom side when a strip is passed through said apparatus;

a fluid coating station spaced from said first roll means, said station including: 7

an applicator roll means positioned to be disposed above and in contact with said strip top side and to rotate in a direction opposite to the direction of rotation of said first roll means;

a fluid feed means positioned in close proximity to said applicator roll means for depositing coating fluid onto said strip top side;

said feed means being located on the upstream portion of said fluid coating station;

a fluid metering means adjustably positioned relative to said applicator roll means to provide a predetermined gap between said metering means and said applicator roll means to provide a uniform fluid thickness on said applicator roll means which in turn will be deposited on said strip top side to be coated;

said fluid metering means being locatedat the downstream strip portion of said fluid coating station;

a second roll means spaced from'said fluid coating station in a direction downstream from said first roll means;

said second roll means positioned to be disposed below and in contact with said strip bottom side.

2. Apparatus in accordance with claim 1 wherein said fluid feed means is positioned to deposit fluid at a location on said applicator roll means in which said roll means rotates in a direction opposite to the direction of fluid emanating from said feed means.

3. Apparatus in accordance with claim 1 in which said applicator roll means is adjustable relative to said first and second roll means to cause a strip to be coated I to be depressed relative to the interfaces of a strip and said first and second roll means.

4. Apparatus in accordance with claim 3 in which said applicator roll means and said metering means are adjustable relative to each other.

5. Apparatus in accordance with claim 1 in which said metering means comprises a roll means.

6. Apparatus in accordance with claim 1 in which said applicator means is at least as wide as a strip to be coated.

7. Apparatus in accordance with claim 1 further including:

means for adjusting said applicator roll means and said first roll means whereby said strip bottom side is maintained substantially free of fluid. 

1. Apparatus for depositing fluid on a strip top side, said apparatus comprising: a first roll means positioned to be disposed below and in contact with a strip bottom side when a strip is passed through said apparatus; a fluid coating station spaced from said first roll means, said station including: an applicator roll means positioned to be disposed above and in contact with said strip top side and to rotate in a direction opposite to the direction of rotation of said first roll means; a fluid feed means positioned in close proximity to said applicator roll means for depositing coating fluid onto said strip top side; said feed means being located on the upstream portion of said fluid coating station; a fluid metering means adjustably positioned relative to said applicator roll means to provide a predetermined gap between said metering means and said applicator roll means to provide a uniform fluid thickness on said applicator roll means which in turn will be deposited on said strip top side to be coated; said fluid metering means being located at the downstream strip portion of said fluid coating station; a second roll means spaced from said fluid coating station in a direction downstream from said first roll means; said second roll means positioned to be disposed below and in contact with said strip bottom side.
 1. Apparatus for depositing fluid on a strip top side, said apparatus comprising: a first roll means positioned to be disposed below and in contact with a strip bottom side when a strip is passed through said apparatus; a fluid coating station spaced from said first roll means, said station including: an applicator roll means positioned to be disposed above and in contact with said strip top side and to rotate in a direction opposite to the direction of rotation of said first roll means; a fluid feed means positioned in close proximity to said applicator roll means for depositing coating fluid onto said strip top side; said feed means being located on the upstream portion of said fluid coating station; a fluid metering means adjustably positioned relative to said applicator roll means to provide a predetermined gap between said metering means and said applicator roll means to provide a uniform fluid thickness on said applicator roll means which in turn will be deposited on said strip top side to be coated; said fluid metering means being located at the downstream strip portion of said fluid coating station; a second roll means spaced from said fluid coating station in a direction downstream from said first roll means; said second roll means positioned to be disposed below and in contact with said strip bottom side.
 2. Apparatus in accordance with claim 1 wherein said fluid feed means is positioned to deposit fluid at a location on said applicator roll means in which said roll means rotates in a direction opposite to the direction of fluid emanating from said feed means.
 3. Apparatus in accordance with claim 1 in which said applicator roll means is adjustable relative to said first and second roll means to cause a strip to be coated to be depressed relative to the interfaces of a strip and said first and second roll means.
 4. Apparatus in accordance with claim 3 in which said applicator roll means and said metering means are adjustable relative to each other.
 5. Apparatus in accordance with claim 1 in which said metering means comprises a roll means.
 6. Apparatus in accordance with claim 1 in which said applicator means is at least as wide as a strip to be coated. 